Use of nanoparticulate organic pigments in paints and coatings

ABSTRACT

A protective and decorative coating composition including about 2 to 10 different colorants which in combination with a resinous composition produce a desired visible coating. A majority of the colorants has a maximum haze of about 10% and exhibits an absorbance peak in the visible spectrum wherein at least about 50% of the total absorbance in the visible spectrum occurs at wavelengths within about 50 nm of the wavelength of the peak absorbance.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 10/165,056, filedJun. 7, 2002, now U.S. Pat. No. 6,875,800 which claims priority under 35U.S.C. § 119 to Provisional Application Ser. No. 60/299,038, filed Jun.18, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

2. Prior Art

The present invention relates to coating compositions containingnanosized colorants, more particularly to coating compositionscontaining a plurality of nanosized colorants having low haze (hightransparency) and a narrow absorbance bandwidth in the visible spectrum.

Paint compositions typically include colorant particles dispersed in aresinous binder. The paint composition may further include reflectivepigments such as aluminum flake or mica or other color effect pigmentcompositions or substrate-hiding materials such as titanium dioxide orzinc oxide or lead oxide. The colorant particles used in conventionalpaints are typically on the order of 0.5 micron in size. Particles ofthis size absorb light at certain wavelengths and scatter light at otherwavelengths. This partial absorption and partial scattering creates adegraded coloration effect when viewed by an observer. Selection of aparticular color for a paint requires blending of such colorants and isdifficult to achieve using conventional colorants because the colorantshave spectral characteristics that overlap one another and because thedegrading scattering effects are compounded. As a result, conventionalpaint compositions typically require blending mixtures selected fromtens or even hundreds of various colorants in order to achieve a desiredpaint color. To create a paint color on demand, paint suppliers maintainnumerous colorants on hand to be able to blend any combination ofcolorants.

When a new color of a paint composition is desired, several colorantsare mixed together and balanced in order to achieve the desired color.This process of producing a colored paint is significantly complicatedwhen the end product is intended to match an existing paint composition.For example, in automotive refinish paints, it is desirable to produce apaint composition that closely matches the paint on an automobile. Thecolor of a paint formulation originally painted on the vehicle duringproduction may change over time and with weathering. In addition, thespectral characteristics of the colorants of the original paintformulation may not be the same as the spectral characteristics of lateravailable colorants. Due to these variabilities, the process ofpreparing a paint composition that closely matches that of an existingautomobile is complicated and often requires trial and error until thedesired color is achieved.

Accordingly, a need remains for a method of preparing a protective anddecorative coating for applying to a substrate and having a color whichis either prespecified or matches a preselected coating compositionselected from a minimum quantity of colorants.

SUMMARY OF THE INVENTION

The present invention includes paint compositions containing nanosizedcolorant particles for producing a desired absorbance in the visiblelight spectrum. The paint compositions include a plurality of colorants,selected from a set of at least 3 colorants, which in combination with abase coating produces a desired color. Preferably, the set of colorantsincludes about 3 to about 10 colorants. A majority and preferably eachof the colorants has a maximum haze of about 10% and a peak absorbancewithin the visible spectrum wherein about 50% of the total absorbance inthe visible spectrum occurs at wavelengths within about 50 nanometers(nm) of the peak absorbance. In a set of at least three colorants, afirst colorant has a maximum absorbance peak in the range of about 400to about 500 nm, a second colorant has a maximum absorbance peak in therange of about 500 to about 600 nm, and a third colorant has a maximumabsorbance peak in the range of about 600 to about 700 nm. By selectingthese colorants in varying amounts, a wide color gamut in the visiblespectrum can be produced. Additional colorants may be needed to producepaint compositions displaying minimal metamerism. Therefore, it ispreferable to include additional colorants also having narrow absorbancepeaks in the visible spectrum and having a maximum haze of about 10%.

The colorants are preferably pigments or dyes, more preferably, organicpigments having a primary particle size of less than about 150 nmpreferably less than about 70 nm, more preferably less than about 30 nm.The pigments may be produced according to conventional pigmentproduction methods and preferably are produced by milling stock organicpigments with grinding media having a particle size of less than about0.5 mm, preferably less than 0.3 mm, and more preferably less than about0.1 mm. The coating compositions may further include substrate-hidingmaterials. The substrate-hiding materials may include graphite,aluminum, mica, or titanium dioxide.

The present invention further includes a substrate-hiding material inthe form of a flake-like assemblage. The flake-like assemblage includesscattering members encapsulated in a resinous polymer. The refractiveindex of the scattering members and the refractive index of the polymerdiffer by greater than about 0.1 and the assemblage has an aspect ratioof about 2 to about 250, preferably greater than 5, more preferablygreater than 10. The scattering members may be titanium dioxide, zincoxide, lead oxide, or air voids.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of particle size versus difference in refractive indexfor colorant particles suspended in a resinous binder;

FIG. 2 is a cross section of a substrate-hiding material made inaccordance with the present invention;

FIG. 3 is a cross section of another embodiment of a substrate-hidingmaterial;

FIG. 4 is a cross section of another embodiment of a substrate-hidingmaterial;

FIG. 5 is a cross section of another embodiment of a substrate-hidingmaterial;

FIG. 6 is a cross section of another embodiment of a substrate-hidingmaterial;

FIG. 7 is a normalized absorbance spectrum for a colorant of the presentinvention;

FIG. 8 is a normalized absorbance spectrum for another colorant of thepresent invention;

FIG. 9 is a normalized absorbance spectrum for another colorant of thepresent invention; and

FIG. 10 is a composite spectrum of the spectra of FIGS. 7-9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of the description hereinafter, it is to be understood thatthe invention may assume various alternative variations and stepsequences, except where expressly specified to the contrary. It is alsoto be understood that the specific devices and processes illustrated inthe attached drawings, and described in the following specification, aresimply exemplary embodiments of the invention. Hence, specificdimensions and other physical characteristics related to the embodimentsdisclosed herein are not to be considered as limiting.

The present invention includes a paint composition containing aplurality of colorants selected from a set of colorants which, when incombination with a resinous binder, produce a desired visible color. Amajority and preferably each colorant has a maximum haze and a narrowabsorbance peak in the visible spectrum. As used herein, the visiblespectrum includes wavelengths of about 400 nm to about 700 nm. Thecoating composition of the present invention preferably includes thecolorants, a resinous binder, and substrate-hiding materials that aredescribed in turn hereinafter. By a “majority” is meant that greaterthan 50% of the number of colorants have the maximum haze and narrowabsorbance peaks. However, a “majority” is also meant to include thesituation of greater than 50% by weight of the colorants based on totalweight of the colorants has the maximum haze and narrow absorbancepeaks.

Colorants

The colorants of the present invention are preferably pigments or dyes,more preferably pigments, having a primary particle size of less thanabout 150 nm, preferably less than about 70 nm, more preferably lessthan about 30 nm. Preferably, the primary particles arenon-agglomerated. The dispersed particle size is the size of theindividual particles (primary particles) or agglomerates of primaryparticles. The coating composition requires the use of at least twocolorants from a set of at least three colorants. The set of colorantsincludes a first colorant having a maximum absorbance peak in the rangeof about 400 to about 500 nm, a second colorant having a maximumabsorbance peak in the range of about 500 to about 600 nm, and a thirdcolorant having a maximum absorbance peak in the range of about 600 toabout 700 nm. A desired color of a paint composition can be producedusing various combinations of colorants from the set of colorants inaddition to the optional use of a white colorant and a black colorant.The set preferably includes about 3 to about 10 colorants. Hence, thetotal number of potential colorants selectable for use in a paintcomposition is about 12.

A majority and preferably each of the colorants has a maximum haze ofabout 10%, preferably a maximum haze of about 1%. Haze is a measurementof the transparency of a material and is defined by ASTM D1003. The hazevalues described herein are determined with a Byk-Gardner TCS (The ColorSphere) instrument having a 500 micron cell path length on colorantsdispersed in butyl acetate. Because the % haze of a liquid sample isconcentration dependent, we specify herein the % haze at a transmittanceof about 15% to about 20% at the wavelength of maximum absorbance. Asgenerally shown in FIG. 1, an acceptable haze may be achieved forrelatively large particles when the difference in refractive indexbetween the particles and the surrounding medium is low. Conversely, forsmaller particles, greater refractive index differences between theparticle and the surrounding medium may provide an acceptable haze.

In addition, the colorants of the present invention exhibit a relativelynarrow band of peak absorbance in the visible spectrum wherein at leastabout 50% or at least about 60% of the total absorbance in the visiblespectrum occurs at wavelengths within about 50 nm of the wavelength ofpeak absorbance. In a preferred embodiment, the first colorant has atleast about 70% (more preferably at least about 80%) of its totalabsorbance in the visible spectrum in the range of about 400 to about500 nm, the second colorant has at least about 70% (more preferably atleast about 75%) of its total absorbance in the visible spectrum in therange of about 500 to about 600 nm and the third colorant has at leastabout 60% (more preferably at least about 70%) of its total absorbancein the visible spectrum in the range of about 600 to about 700 nm. Thecombined features of low haze and narrow maximum absorbance peak in thevisible spectrum of the colorants of the present invention create adefined color effect. Accordingly, a relatively small number ofdifferent colorants (2 to 12) may be used in combination to produce adesired color in a paint composition. At least two colorants are neededto produce a paint composition having a desired color. Due to the natureof human color vision, two colored articles may be appear the same colorunder illumination with a given light source, even though they may havedifferences in their reflection spectra. Because of the differences intheir reflection spectra, these same two articles may appear to bedifferent from each other in color under a different light source. Thisilluminant-dependent color matching phenomenon, referred to asmetamerism, may be undesirable particularly for automotive refinishpaint compositions that appear to match an original automotive paintwhen indoors but fail to match outdoors. By selecting more than two ofthe colorants of the present invention, metamerism can be avoided sincethe visible spectra of the colorants can be combined to closely matchthe spectrum of a desired color due to the absence of scatteringdegradation with these colorants and their spectral selectivity.

In certain coating compositions containing metallic pigments, it may bedesirable to include colorants which do not have the properties of themaximum haze and narrow absorbance peak. For example, conventionalmetallic paint which appears cyan when viewed directly (on face) fromreflected light appears red when viewed at an angle (flop) fromscattered light. The colorants of the present invention have minimalscatter. Hence, a coating composition containing only the colorants ofthe present invention may appear black on flop. In order to create acolor effect mimicking conventional paint, additional colorants may beadded to the coating composition so that on flop, the coating appears adesired color other than black. Accordingly, the inclusion ofconventional colorants in a coating composition along with the colorantsof the present invention having the low haze and narrow peak absorbanceband is optional.

Suitable pigment compositions that may be used in the present inventionto produce the colorants include azo (monoazo, disazo, β-naphthol,naphthol AS, salt type (lakes), benzimidazolone, condensation, metalcomplex, isoindolinone, isoindoline) and polycyclic (phthalocyanine,quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo,anthraquinone (indanthrone, anthrapyrimidine, flavanthrone, pyranthrone,anthanthrone, dioxazine, triarylcarbonium, quinophthalone) pigments, andmixtures thereof. In order to achieve the desired haze (minimalscattering) of no more than about 10% haze, the colorants have aparticle size of about 150 nm or less, preferably less than about 70 nmand, more preferably, less than about 30 nm. Preferably, the particlesare non-agglomerated.

Particles of the colorant may be prepared by milling bulk colorants,e.g., organic pigments, with milling media having a particle size ofless than about 0.5 mm, preferably less than 0.3 mm and more preferablyabout 0.1 mm or smaller. The pigment particles are milled tonanoparticulate sizes in a high energy mill in an organic solventsystem, such as butyl acetate using a dispersant, such as Solsperse®32,500 available from Avecia, Inc. of Wilmington, Del. or in water usinga dispersant, such as Solsperse® 27,000 available from Avecia, Inc. withan optional polymeric grinding resin. Other suitable methods ofproducing the colorants of the present invention includecrystallization, precipitation, gas phase condensation, and chemicalattrition (i.e., partial dissolution).

Resinous Binder

The decorative and protective coating composition of the presentinvention includes a resinous binder. Conventional resinous binders maybe used with the colorants described herein in automotive OEMcompositions, automotive refinish compositions, industrial coatings,architectural coatings, electrocoatings, powder coatings, coil coatings,and aerospace coatings.

Suitable resinous binders include a curable coating compositionincluding components such as hydroxyl or carboxylic acid-containingacrylic copolymers and hydroxyl or carboxylic acid-containing polyesterpolymers and oligomers and isocyanate or hydroxyl-containingpolyurethane polymers, or amine or isocyanate-containing polyureas whichcan enhance cure rate, appearance and other physical properties of thecured coating.

The acrylic polymers, if used, are typically copolymers of acrylic acidor methacrylic acid or hydroxyalkyl esters of acrylic or methacrylicacid such as hydroxyethyl methacrylate or hydroxypropyl acrylate withone or more other polymerizable ethylenically unsaturated monomers suchas alkyl esters of acrylic acid including methyl methacrylate and2-ethyl hexyl acrylate, and vinyl aromatic compounds such as styrene,alpha-methyl styrene and vinyl toluene. The ratio of reactants andreaction conditions are selected to result in an acrylic polymer withpendant hydroxyl or carboxylic acid functionality.

Besides acrylic polymers, the curable coating composition of the presentinvention can contain a polyester polymer or oligomer. Such polymers maybe prepared in a known manner by condensation of polyhydric alcohols andpolycarboxylic acids. Suitable polyhydric alcohols include ethyleneglycol, neopentyl glycol, trimethylol propane and pentaerythritol.

Suitable polycarboxylic acids include adipic acid, 1,4-cyclohexyldicarboxylic acid and hexahydrophthalic acid. Besides the polycarboxylicacids mentioned above, functional equivalents of the acids such asanhydrides where they exist or lower alkyl esters of the acids such asthe methyl esters may be used. Also, small amounts of monocarboxylicacids such as stearic acid may be used.

Hydroxyl-containing polyester oligomers can be prepared by reacting ananhydride of a dicarboxylic acid such as hexahydrophthalic anhydridewith a diol such as neopentyl glycol in a 1:2 molar ratio.

Where it is desired to enhance air-drying, suitable drying oil fattyacids may be used and include those derived from linseed oil, soya beanoil, tall oil, dehydrated castor oil or tung oil.

The polyesters are made to contain free terminal hydroxyl and/orcarboxyl groups that are available for further crosslinking reactions.

Polyurethane polymers containing terminal isocyanate or hydroxyl groupsmay also be used. The polyurethane polyols or NCO-terminatedpolyurethanes that can be used are those prepared by reacting polyolsincluding polymeric polyols with polyisocyanates. Thepolyurea-containing terminal isocyanate or primary or secondary aminegroups which can be used are those prepared by reacting polyaminesincluding polymeric polyamines with polyisocyanates. Thehydroxyl/isocyanate or amine/isocyanate equivalent ratio is adjusted andreaction conditions selected to obtain the desired terminal group.Examples of suitable polyisocyanates are those described in U.S. Pat.No. 4,046,729 at column 5, line 26 to column 6, line 28, herebyincorporated by reference. Examples of suitable polyols are thosedescribed in U.S. Pat. No.4,046,729 at column 7, line 52 to column 10,line 35, hereby incorporated by reference. Examples of suitablepolyamines are those described in U.S. Pat. No. 4,046,729 at column 6,line 61 to column 7, line 32 and in U.S. Pat. No. 3,799,854 at column 3,lines 13 to 50, both hereby incorporated by reference.

Suitable curing agents for the curable coating composition includeaminoplast resins and phenoplast resins and mixtures thereof, as curingagents for OH and COOH, and amide and carbamate functional groupcontaining materials. Examples of aminoplast and phenoplast resinssuitable as curing agents in the curable compositions of the presentinvention are those described in U.S. Pat. No. 3,919,351 at col. 5, line22 to col. 6, line 25, hereby incorporated by reference.

Polyisocyanates and blocked polyisocyanates as curing agents for OH andprimary and/or secondary amino group containing materials are well knownin the art. Examples of polyisocyanates and blocked isocyanates suitablefor use as curing agents in the curable compositions of the presentinvention are those described in U.S. Pat. No. 4,546,045 at col. 5,lines 16 to 38; and in U.S. Pat. No. 5,468,802 at col. 3, lines 48 to60, both hereby incorporated by reference.

Anhydrides as curing agents for OH and primary and/or secondary aminogroup containing materials are well known in the art. Examples ofanhydrides suitable for use as curing agents in the curable compositionsof the present invention are those described in U.S. Pat. No. 4,798,746at col. 10, lines 16 to 50; and in U.S. Pat. No. 4,732,790 at col. 3,lines 41 to 57, both hereby incorporated by reference.

Polyepoxides as curing agents for COOH functional group containingmaterials are well known in the art. Examples of polyepoxides suitablefor use as curing agents in the curable compositions of the presentinvention are those described in U.S. Pat. No. 4,681,811 at col. 5,lines 33 to 58, hereby incorporated by reference.

Polyacids as curing agents for epoxy functional group containingmaterials are well known in the art. Examples of polyacids suitable foruse as curing agents in the curable compositions of the presentinvention are those described in U.S. Pat. No. 4,681,811 at col. 6, line45 to col. 9, line 54, hereby incorporated by reference.

Polyols, that is, material having an average of two or more hydroxylgroups per molecule, can be used as curing agents for NCO functionalgroup containing materials and anhydrides and esters and are well knownin the art. Examples of said polyols are those described in U.S. Pat.No. 4,046,729 at col. 7, line 52 to col. 8, line 9; col. 8, line 29 tocol. 9, line 66; and in U.S. Pat. No.:3,919,315 at col. 2, line 64 tocol. 3, line 33, both hereby incorporated by reference.

Polyamines can also be used as curing agents for NCO functional groupcontaining materials and for carbonates and unhindered esters and arewell known in the art. Examples of polyamines suitable for use as curingagents in the, curable compositions of the present invention are thosedescribed in U.S. Pat. No. 4,046,729 at col. 6, line 61 to col. 7, line26, hereby incorporated by reference.

The decorative and protective coating composition may be used as asingle coating, as a clear top coating composition, as a base coating ina two-layered system, a layers of a multi-layered system including aclear top coating composition, colorant layer and base coatingcomposition, or as a primer layer.

Substrate-hiding Materials

The decorative and protective coating composition of the presentinvention includes substrate-hiding materials. The hiding materials arepreferably in platelet form and include graphite, alumina; mica, or ascattering member. A preferred hiding particle is a polymer encapsulatedscattering member.

The polymer encapsulated scattering pigment may be in the form of aflake-like assemblage as shown in FIG. 2. The flake-like assemblage 2includes scattering members 4 encapsulated in a resinous polymer 6. Thescattering members 4 may be titanium dioxide, zinc oxide, lead oxide, orair voids or combinations thereof. A difference in refractive indexbetween the scattering members 4 and the polymer 6 is greater than about0.1, preferably greater than about 1. The flake-like assemblage 2 has anaspect ratio of about 2 to 250, preferably greater than about 5, morepreferably greater than about 10. The volume ratio of the scatteringmembers 4 to the polymer 6 is about 1:10 to about 10:1. When theflake-like assemblages 2 are included in a paint composition and thepaint is applied to a substrate, the flake-like assemblages 2 tend toalign with the substrate and with each other in parallel along theirlongest dimensions to create multidirectional scattering of light in thepaint composition.

In an alternative embodiment, shown in FIG. 3, a flake-like assemblage12 includes the scattering members 4 dispersed in resinous polymer 6. Acolorant layer 18 is provided on each surface of the polymer 6. Thetotal thickness of the colorant layers 18 preferably is about 2% toabout 90% of the thickness of the total flake-like assemblage 12. Thecolorant layers 18 include colorant particles (not shown) dispersed in aresinous polymer that may be the same or different polymer as theresinous polymer 16. The colorant particles preferably include pigmentparticles having sizes less than about 150 nm and preferably are thecolorants described above. By including the colorant layer 18 adjacentto the scattering members 4, light which reaches the scattering members4 necessarily has passed through a region containing the colorants ofthe present invention. This ensures that light scattered from theflake-like assemblage 12 will have been subjected to the lightabsorbance of the colorant particles.

In another embodiment shown in FIG. 4, a flake-like assemblage 22includes a pair of layers 24 including the scattering members 4dispersed in the resinous polymer 6. Layers 26 of the colorant particlescover the layers 24. Intermediate to the layers 24 is a layer 30containing dark pigments (not shown). The dark colored layer 30 absorbsthat light which may be forward scattered by the scattering members 4.Alternatively, a flake-like assemblage 32 shown in FIG. 5 may includethe layers 24 and 30 without the outer layers 26.

Another embodiment of a flake-like assemblage 42 is shown in FIG. 6including the scattering members 4 dispersed in the polymer 6. Alsodispersed in the polymer 6 are filler materials 44, such as silica,which serve to maintain the scattering members 4 spaced apart from eachother. Preferably, the scattering members 4 are sized about 200 to 300nm and the filler particles 44 are about 150 nm in size. The polymer 6typically may have a refractive index of about 1.35 to about 1.8 andscattering members of titanium dioxide have a refractive index of about2.1 to about 2.7. The titanium dioxide scattering members may be coatedwith a passivating layer of silica or alumina. When the filler particles44 are silica, which has a refractive index of about 1.46, the fillerparticles 44 may increase the difference in refractive index between thesurrounding composite of resinous binder with silica and the scatteringmembers 4.

Color Matching Methods

The present invention further includes a method of color matching apreselected coating. According to the method of the present invention,the visible color of the preselected coating is determined by measuringthe absorbance or reflectance of the preselected coating across therange of wavelengths corresponding to visible light. Preferably, theabsorbance or reflectance of the preselected coating is determined usinga spectrophotometer and a curve of the absorbance or reflectance acrossthe range of wavelengths corresponding to visible light is produced.This curve is referred to as the visible absorbance or reflectancespectrum. Two or more of the colorants of the present invention areselected which in appropriate concentrations in combination with aresinous binder produce a colored coating composition having a visibleabsorbance or reflectance-spectrum closely matching that of thepreselected coating. It is believed that a set of 10 different colorantsof the present invention in addition to a black colorant and a whitecolorant may be used to produce colors of preselected coatings.

The present invention also includes a method of creating a new color ofa coating composition. The colorants of the present invention havingknown spectral characteristics may be combined with a resinous binder toproduce a desired color.

The invention will further be described by reference to the followingexamples.

EXAMPLE 1

Chromothal® Yellow BGN (Ciba Specialty Chemicals, Inc., High Point,N.J.) was milled and dispersed on an Advantis® mill (Draiswerke, Inc.,Mahwah, N.J.) using Solsperse® dispersants (Avecia, Inc., Wilmington,Del.) and Zonyl® (polytetrafluoroethylene) (E.I. duPont de Nemours andCompany, Wilmington, Del.), Table 1 sets forth the milling componentsand conditions. For analysis, the final colorant was diluted withn-butyl acetate. Table 2 lists the properties, of the final colorant.The average primary particle size was obtained with a Philips CM12transmission electron microscope (TEM) at 100 kV. The % haze wasmeasured with a Byk-Gardner TCS (The Color Sphere) instrument having a500 micron cell path length. The visible absorption spectrum of thepigment composition was obtained with a Perkin-Elmer, Lamda 2, UV/visspectrometer in a cuvette with 1 cm path length and is reproduced inFIG. 7 with the spectrum normalized to 1 at the wavelength of maximumabsorbance. The crosshatched region represents the integrated absorbanceover those wavelengths within a 100 nm wavelength range centered at thewavelength of maximum absorbance and within the visible range of 400 to700 nm. With this colorant, 85% of the total absorbance in the visiblespectrum occurs between the wavelengths of 400 to 500 nm.

TABLE 1 Example % of mill base 1 2 3 4 5 6 7 Pigment 8.17 13.56 13.249.34 5.00 9.20 4.80 Solsperse ® 5000 0 0 2.07 0.89 0 0 0 Solsperse ®22000 0 0 0 0 0 0.18 0.94 Zonyl ® FSO 0.12 0 0 0 0 0.00 0.00 Solsperse ®32500 0 33.88 29.94 41.12 2.59 0 0 Solsperse ® 31845 0 0 0 0 0 26.18 0Dispersant* 10.73 0 0 0 0 0 13.83 Acrylic grind polymer** 30.20 0 0 033.94 17.92 49.06 n-butyl acetate 37.60 35.04 48.86 36.60 38.98 31.1822.68 Dowanol PM acetate 13.23 17.52 5.89 12.05 19.49 15.34 8.70 Millresidence time (min.) 185 37 55 103 63 443 319 Media size (mm) 0.3 0.30.3 0.2 0.2 0.3 0.2 *A quaternary ammonium group containing polymerprepared as generally described in U.S. Pat. No. 6,365,666 B, by atomtransfer radical polymerization techniques from the following monomerson a weight basis: 4.7% glycidyl methacrylate, 20.3% benzylmethacrylate,14.1% butylmethacrylate, 52.3% 2-ethyhexylmethacrylate and 7.1% ofhydroxypropyl methacrylate. The polymer was quaternized with the lacticacid salt of dimethethanol amine. The polymer has an M(n) of 9505 and anM(w) of15,445 as determined by gel permeation chromatography using apolystyrene standard. **An acrylic polymer iminated with propylene imineprepared by solution polymerization techniques from the followingmonomers on a weight basis: 29.32% styrene, 19.55% 2-ethylhexylacrylate, 19.04% butyl methacrylate, 9.77% 2-hydroxyethyl acrylate,1.86% methacrylic acid, and 0.59% acrylic acid.

TABLE 2 Example Properties 1 2 3 4 5 6 7 TEM primary 100 20 30 20 60 9050 particle size (nm) % Haze* 9.18 0.17 0.13 0.33 0.71 3.03 2.25 % IA**75 70 67 67 59 66 75 % Total solids 31.42 30.32 38.43 24.9 41.28 32.1237.18 (by weight)*** % Pigment 8.92 7.98 9.73 8.75 4.97 8.48 5.55 (byweight)*** *Percent haze at a transmittance of about 17.5% at thewavelength of maximum absorbance. **Percent of integrated absorbancewithin the visible range that lies within a 100 nm wavelength rangecentered at the wavelength of maximum absorbance. ***The colorants wereadjusted to attain these final % solids and % pigment values.

EXAMPLE 2

A magenta pigment of Hostaperm® Pink EB Trans (Clariant Corporation,Charlotte, N.C.) was milled and dispersed and analyzed as in Example 1.See Tables 1 and 2. In FIG. 8, the visible absorption spectrum isnormalized to 1 at the wavelength of maximum absorbance. Thecrosshatched region represents the integrated absorbance over thosewavelengths within a 100 nm wavelength range centered at the wavelengthof maximum absorbance and within the visible range of 400 to 700 nm.With this colorant, 75% of the total absorbance in the visible spectrumoccurs between the wavelengths of 500 to 600 nm.

EXAMPLE 3

A cyan pigment of Heliogen® Blue L 7081D, (BASF Corporation, MountOliver, N.J.) was milled and dispersed and then analyzed as inExample 1. In FIG. 9, the spectrum is normalized to 1 at the wavelengthof maximum absorbance. The crosshatched region represents the integratedabsorbance over those wavelengths within a 100 nm wavelength rangecentered at the wavelength of maximum absorbance and within the visiblerange of 400 to 700 nm. With this colorant, 70% of the total absorbancein the visible spectrum occurs between the wavelengths of 600 to 700 nm.

FIG. 10 includes the spectra of FIGS. 7-9 without the crosshatchedregions. The relatively narrow absorbance peaks of the colorants ofExamples 1-3 and minimal overlap therebetween is demonstrated in FIG. 10(Example 1, dotted line; Example 2, dashed line; Example 3, solid line).

EXAMPLE 4

A green pigment of Monolite Green 860/Monastrol Green 6Y (Avecia) wasmilled and dispersed and analyzed as in Example 1. See Tables 1 and 2.

EXAMPLE 5

A violet pigment of Monolite Blue 3R (Avecia) was milled and dispersedand analyzed as in Example 1. See Tables 1 and 2.

EXAMPLE 6

A red-orange pigment of 12-4215 Hostaperm® Scarlet GO Trans (Clariant)was milled and dispersed and analyzed as in Example 1. See Tables 1 and2.

EXAMPLE 7

A yellow-orange pigment of Irgazin® Yellow 3RLTN (Ciba) was milled anddispersed and analyzed as in Example 1 See Tables 1 and 2.

EXAMPLE 8

A metal panel (C1) was coated with a blue paint containing the followingPPG Industries, Inc. (Pittsburgh, Pa.) automotive refinish mixing bases(all percentages are weight %): DMD1676 (blue) 65.14%, DMD1684 (white)15.49%, DMD614 (blue) 6.34%, DMD1683 (black) 3.17%, DBX1689 (clear)9.86%. The color of this panel was non-metamerically matched and acorresponding panel (N1) was coated with a paint containing DMD1684(white) 14.75%, DMD1683 (black) 3.00%, the cyan colorant of Example 335.25%, the violet colorant of Example 5 6.00%, and DBX1689 (clear)41.00%. The CIE color of the panels (under D65 illumination, 10°observer) and the color differences (under three illuminants) are shownin Table 3a and 3b.

TABLE 3a Panel L* a* b* C* h° C1 28.39 −12.01 −34.86 36.87 250.99 N128.25 −12.12 −33.85 35.95 250.29

TABLE 3b Difference formula D65-10° A-10° CWF-10° ΔE*ab 1.03 1.36 1.31ΔE*cmc (2:1) 0.52 0.55 0.60

EXAMPLE 9

A metal panel (C2) was coated with a salmon-peach colored paintcontaining the following PPG Industries, Inc. automotive refinish mixingbases (all percentages are weight %): DMD616 (orange) 37.64%, DMD1684(white) 16.00%, DMD1679 (red) 5.96%, DMD666 (yellow) 1.13%, DMD1683(black) 1.00%, DBX1689 (clear) 38.27%. A good visual match to the colorof this panel was produced with a corresponding panel (N2), coated witha paint containing DMD1684 (white) 33.75%, DMD1683 (black) 1.25%, thered-orange colorant of Example 6 27.00%, the yellow colorant of Example1 5.50%, and DBX1689 (clear) 32.50%. The CIE color of the panels (underp65 illumination, 10° observer) and the color differences (under threeilluminants) are shown in Table 4a and 4b below.

TABLE 4a Panel L* a* b* C* h° C2 52.74 39.67 28.21 48.68 35.42 N2 53.0539.94 28.26 48.93 35.28

TABLE 4b Difference formula D65-10° A-10° CWF-10° ΔE*ab 0.42 0.73 1.10ΔE*cmc (2:1) 0.20 0.55 0.81

EXAMPLE 10

A metal panel (C3) was coated with a light-green paint comprised of thefollowing PPG Industries, Inc. automotive refinish mixing bases (allpercentages are weight %): DMD1684 (white) 41.07%, DMD1678 (green)35.71%, DMD648 (black) 8.93%, DMD644 (yellow) 2.50%, DBX1689 (clear)11.79%. A good visual match to the color of this panel was produced witha corresponding panel (N3) coated with a paint containing DMD1684(white) 54.02%, the green colorant of Example 4 19.35%, theyellow-orange colorant of Example 7 3.77%, and DBX1689 (clear) 22.86%.The CIE color of the panels (under D65 illumination, 10° observer) andthe color differences (under three illuminants) are shown in Tables 5aand 5b below.

TABLE 5a Panel L* a* b* C* h° C3 64.40 −45.54 15.71 48.18 160.97 N364.38 −45.22 16.16 48.02 160.34

TABLE 5b Difference formula D65-10° A-10° CWF-10° ΔE*ab 0.55 0.99 0.65ΔE*cmc (2:1) 0.29 0.49 0.33

EXAMPLE 11

A metal panel (C4) was coated with a red (fuchsia) paint comprised ofthe following PPG Industries, Inc. automotive refinish mixing bases (allpercentages are weight %): DMD616 (orange) 32.68%, DMD1605 (magenta)26.40%, DMD1684 (white) 6.60%, DMD648. (black) 0.99%, DBX1689 (clear)33.33%. A good visual match to the color of this panel was produced witha corresponding panel (N4), coated with a paint containing DMD1684(white) 11.25%, the red-orange colorant of Example 6 28.00%, the magentacolorant of Example 2 15.75%, and DBX1689. (clear) 45.00%. The CIE colorof the panels (under D65 illumination, 10° observer) and the colordifferences (under three illuminants) are shown in Tables 6a and 6bbelow.

TABLE 6a Panel L* a* b* C* h° C4 34.45 52.15 16.27 54.63 17.33 N4 34.8151.94 15.79 54.29 16.91

TABLE 6b Difference formula D65-10° A-10° CWF-10° ΔE*ab 0.64 1.72 1.65ΔE*cmc (2:1) 0.34 0.70 1.00

EXAMPLE 12

A metal panel (C5) was coated with a metallic green paint comprised ofthe following PPG Industries, Inc. automotive refinish mixing bases (allpercentages are weight %): DMD1678 (green) 41.53%, DMD1686 (finealuminum) 27.68%, DMD1687 (medium course aluminum) 12.11%, DMD644(yellow) 6.57%, DMD1683 (black) 3.11%, DMD1684 (white) 2.08%, DBX1689(clear) 6.92%. A good visual match to the color of this panel wasproduced with a corresponding panel (N5) coated with a paint containingDMD633 (medium aluminum) 27.50%, DMD1684 (white) 2.50%, DMD1683 (black)2.50%, the green colorant of Example 4 15.00%, the yellow-orangecolorant of Example 7 5.00%, and DBX1689 (clear) 47.50%. The CIE colorof the panels (under D65 illumination, 10° observer) and the colordifferences (under three illuminants) are shown in Tables 7a and 7bbelow.

TABLE 7a Panel L* a* b* C* h° C5 47.13 −26.81 14.09 30.29 152.27 N546.82 −25.70 13.89 29.21 151.60

TABLE 7b Difference formula D65-10° A-10° CWF-10° ΔE*ab 1.17 0.48 0.57ΔE*cmc (2:1) 0.61 0.32 0.32

EXAMPLE 13

A metal panel (C6) was coated with a green paint comprised of thefollowing PPG Industries, Inc. automotive refinish mixing bases (allpercentages are weight %): DMD1678 (green) 74.21%, DMD1676 (blue)19.35%, DMD1684 (white) 6.34%, DMD1683 (black) 0.10%. A good visualmatch to the color of this panel was produced with a corresponding panel(N6) coated with a paint containing DMD1684 (white) 5.75%, DMD1683(black) 1.00%, the green colorant of Example 4 34.00%, the yellowcolorant of Example 1 3.25%, the cyan colorant of Example 3 9.00%, andDBX1689 (clear) 47.00%. The CIE color of the panels (under D65illumination, 10° observer) and the color differences (under threeilluminants) are shown in Tables 8a and 8b below.

TABLE 8a Panel L* a* b* C* h° C6 26.67 −44.03 0.81 44.04 178.95 N6 27.38−45.16 0.85 45.17 178.92

TABLE 8b Difference formula D65-10° A-10° CWF-10° ΔE*ab 1.33 2.07 1.68ΔE*cmc (2:1) 0.66 0.94 0.94

EXAMPLE 14

A composition comprising a dispersion of titanium-dioxide in acrylicmonomers was prepared via the following procedure. 780 g Ti-Pure R-706titanium dioxide pigment (Du Pont) and 6 g cellulose acetate butyratefrom Sigma-Aldrich Company, Milwaukee, Wis., were dispersed using arotary stirrer, fitted with a 2.5 inch diameter cowles blade, at 1100revolutions per minute, in 160.5 g 1,4-butanediol diacrylate, 80.0 gpentaerythritol tetraacrylate, 80.5 g ethoxylated (4) pentaerythritoltetraacrylate, all from Sartomer Company, Exton, Pa. and 18 g acrylicacid from Sigma-Aldrich Company, Milwaukee, Wis. To the mixture wasadded a further 97.5 g pentaerythritol tetraacrylate (Sartomer), 12 gcellulose acetate butyrate from (Sigma-Aldrich) and 108 g n-butylacetate. An ultraviolet radiation curable composition was prepared viathe following procedure. 166 g n-butyl acetate and 5.1 gdiphenyl(2,4,6-trimethylbenzoyl)phosphineoxide/2-hydroxy-2-methylpropiophenone 50/50 blend (Sigma-Aldrich) wereadded to 500 g of the dispersion of titanium dioxide in acrylicmonomers. The mixture was filtered using a 5 micron nylon filter bag.500 g of the ultraviolet radiation curable composition was applied via aslot-die coater from Frontier Technologies, Towanda, Pa. to apolyethylene terephthalate substrate and dried at 150° F. for 12 secondsand then ultraviolet radiation cured using a 100 W mercury lamp. Thehardened film was then removed from the polyethylene terephthalatesubstrate.

The hardened film was processed into a fine powder by dry milling for 10minutes with a mortar and pestle. 38.41 g of the milled powder (50%pigment on total solids) was added to 84.57 g of DCU2042 and 18.54 g ofDT870 (a clearcoat package and a solvent reducer package available fromPPG Industries, Inc. as one component of a two component binder system.The milled powder was dispersed within the binder by shaking on a RedDevil shaker for 20 minutes. After completing the dispersing phase,24.01 g of the second component, DCX61, (a crosslinking packageavailable from PPG Industries, Inc.) was added, and the composition wasre-shaken for 5 minutes.

EXAMPLE 15

Example 14 was repeated except that 0.47 g of stearyl acetate was addedwith the acrylic acid.

EXAMPLE 16: COMPARATIVE

A comparative coating composition to Examples 14 and 15 was prepared byadding 38.89 g of a preprocessed dispersion of rutile titanium dioxide,D700, (a white mixing base available from PPG Industries, Inc.) to onecomponent of the same two component binder system used in Example 14,and then shaken on a Red Devil shaker for 20 minutes. After beingshaken, the second component was added, and the composition wasre-shaken for 5 minutes.

EXAMPLE 17

19.20 g of a 5% pigment solids dispersion of the colorant of Example 2was added to the coating composition of Example 14. The tinted coatingcomposition was shaken on a Red Devil shaker for 5 minutes, equilibratedfor 5 minutes, and drawn down over Form 1B Leneta paper (Penopacavailable from The Leneta Company, Ho-Ho-Kus, N.J.) with a 48 gauge,wire drawdown rod (wire-wound rods available from Paul N. Gardner Co.Inc., Pompano Beach, Fla.). This drawdown was cured under ambientconditions for 24 hrs. After curing, the color and opacity of thedrawdown were measured with a Minolta CM-3600d spectrophotometer. Thecolor and opacity data are shown in Table 9.

EXAMPLE 18

Example 17 was repeated using the coating composition of Example 15.

EXAMPLE 19: COMPARATIVE

Example 17 was repeated using the comparative coating composition ofExample 16.

Table 9 shows that at about the same opacity, Example 17 and moreespecially, Example 18 show the advantage of being more red (larger a*)than the comparative Example 19. Therefore, equal hiding with less colordilution from white pigment was found with Example 17, and especiallywith Example 18, than with Example 19.

TABLE 9 Drawdown L* a* b* C* h° % opacity Example 17 57.05 43.74 −20.4148.27 334.98 93.74 Example 18 52.06 48.04 −19.42 51.81 337.99 92.13Example 19 58.32 42.12 −19.87 46.57 334.74 92.53

It will be readily appreciated by those skilled in the art thatmodifications may be made to the invention without departing from theconcepts disclosed in the foregoing description. Such modifications areto be considered as included within the following claims unless theclaims, by their language, expressly state otherwise. Accordingly, theparticular embodiments described in detail herein are illustrative onlyand are not limiting to the scope of the invention which is to be giventhe full breadth of the appended claims and any and all equivalentsthereof.

1. A flake assemblage comprising a plurality of scattering members encapsulated in a resinous polymer, wherein a difference in refractive index between said scattering members and said polymer is greater than about 0.1 and said assemblage has an aspect ratio of about 2 to about 250; wherein the scattering members are not comprised of composite materials.
 2. The assemblage of claim 1 having an aspect ratio greater than about
 5. 3. The assemblage of claim 1 having an aspect ratio greater than about
 10. 4. The assemblage of claim 1 wherein the difference in refractive index between said scattering members and said polymer is greater than about 0.5.
 5. The assemblage of claim 1 wherein the difference in refractive index between said scattering members and said polymer is greater than about
 1. 6. The assemblage of claim 1 wherein said scattering members are titanium dioxide, zinc oxide, lead oxide, or air voids.
 7. The assemblage of claim 1 wherein the ratio by volume of said resinous polymer to said scattering members is about 1:10 to about 10:1.
 8. The assemblage of claim 1 wherein said scattering members are present in a first layer and the assemblage further comprise at least one exterior colorant layer.
 9. The assemblage of claim 8 wherein said at least one colorant layer is about 2 to about 90% of the thickness of said particles.
 10. The assemblage of claim 8 wherein said colorant layer comprises colorant particles dispersed in a resinous polymer.
 11. The assemblage of claim 10 wherein said colorant particles comprise pigment particles having particle sizes of about 150 nm.
 12. The assemblage of claim 8 wherein said assemblage further comprises an intermediate layer comprising a dark pigment disposed between a pair of said first layers.
 13. A protective and decorative coating composition for applying to a substrate comprising a first coating composition and a plurality of flake assemblages for hiding a substrate, said assemblages comprising a plurality of scattering members encapsulated in a resinous polymer, wherein a difference in refractive index between said scattering members and said polymer is greater than about 0.1 and said assemblage has an aspect ratio of about 2 to about 250; wherein the scattering members are not comprised of composite materials.
 14. The coating composition of claim 13 wherein said resinous polymer comprises a curable coating composition. 